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Thread: Epson V750 and V850

  1. #1

    Epson V750 and V850

    Hey Folks,
    Been toying with the idea of getting one of these scanners for 5x7 film. I understand that the claimed scan resolution for these scanners are 6200 or 6400 ppl but I understand that this is an interpolated value and the real resolution is in the neighborhood of 2400 ppl. It is also my understanding that some scanners have differing resolution based on the area being scanned i.e. the larger area scanned, the lower the resolution. I have not heard that these scanners do that but donít know that they donít. Will the 2400 resolution cover the 5x7? Anyone that uses these scanners can they clue me in?
    Thanks & Cheers, Richard

  2. #2

    Re: Epson V750 and V850

    I'm not an expert on the hardware of these scanners but have scanned a fair amount of both 5x7 and 8x10 on my V750. The limiting factor on these scanners is the preciseness of the focus plane. I've never taken the time to get one of those better scanning holders and shimmed it to get the focus as nailed as it can be, but am pretty sure that's the way to go for eeking out the most quality from one of these.

    Short answer, yes 2400 will cover 5x7 but in my experience it will only look good up to about 20x24. When I've attempted to make 30 x 40s from this scanner and then compared it to a 2000 dpi scan from an imacon or drum. the epson gets trundled soundly.

    I think it's a great value scanner for proof prints and smallish prints, or medium easel sized prints if you're not going to do a side by side comparison with a higher end scanner.

  3. #3

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    Re: Epson V750 and V850

    Quote Originally Posted by Chester McCheeserton View Post
    The limiting factor on these scanners is the preciseness of the focus plane.
    If you don't have a 5x7 holder then you scan on bed with the area guide, so you have total focus precission, as the LR lens is focused on the glass surface. If you have curled film you may wet mount on bed.

  4. #4

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    Re: Epson V750 and V850

    Quote Originally Posted by Richard Martel View Post
    claimed scan resolution for these scanners are 6200 or 6400 ppl but I understand that this is an interpolated value and the real resolution is in the neighborhood of 2400 ppl.
    No...

    It is true 6400 samples per inch without interpolation, the sensor has +40k rgb pixels. The effective optic yield of the V700/750/800/850 is 2900dpi in the horizontal direction and 2300dpi in the vertical direction when using holders, the average is 2400 to 2600 effective.

    When using holders the scaner uses the High Resolution lens that covers 5.9" scan width, problem is that the Epson does not include holders for 5x7" (only for 4x5"), so you need a holder if wanting top resolution for 5x7".

    The High Resolution lens is focused a few mm over the glass bed, where holders hold film separated from glass.

    _____

    For 5x7 and 8x10 you may use the area guide, a mask you place on bed. In that situation the scanner uses the Low Resolution lens that covers the entire bed width, but the sampling density is lowered to 4800dpi, with effective optic yield proportionally lowered to around 1900dpi effective. This is not bad at all, because a 5x7 drum scan probably will be made at 2000dpi, (4000, if offered, is quite expensive), and even a drum will have a loss from the sampling rate to effective optic dpi.

    When you scan on bed you have to place the emulsion side down, in contact with glass to avoid newton rings, you may even wet mount directly on glass bed. If you scratch the glass bed this can be replaced for some $50.

    That Low Resolution lens is focused exactly on the glass surface, so you ensure focus.



    Quote Originally Posted by Richard Martel View Post
    Will the 2400 resolution cover the 5x7?
    >> 6400 resolution with holders and 4800 on bed. Effective optic yield is 2500 or 1900. You have to purchase a 5x7" holder around, because epson only makes holders until 4x5".

    >> Take the V800 or V850 because the LED illumination is very convenient, no lamp pre-heating delays before starting, and it does not require much lamp calibrations, as LED is stable over time.

    >> The V700 and V800 lack a better lens coating than the 750/850 has (that may have little importance) and have a lower Silverfast version (the non "Plus" one) that lacks Multi-Exposure, IMHO this is only important to recover velvia deep shadows, anyway you may upgrade later the V800 silverfast version to the Plus one.


    _______


    Scanner operator is very important. Scan all histogram in 16 bits/channel, save the image in TIFF mode to not loss the 16bits, edit/sharpen at 16bits and high res, reduce image size with with "Bicubic, special for reductions" option, sharpen again with care. User edition is critical.


    _______

    This is a 8x10 scan on bed, slightly sharpened in PS, you may see what results you may obtain scanning on bed.

    https://www.flickr.com/photos/125592...5/32535835184/

    Once you have the scanner you may scan a 4x5" negative on bed and in the holder to see if you need the 5x7 holder.

    Pro scanners usually make a very smart/good sharpening in the machine. The Epson is not intended for Pro users scanning all day long, it's Prosumer gear IMHO, so you have to do that sharpening in Ps: No problem, a photographer probably prefers making that sharpening manually from the raw data.

  5. #5

    Re: Epson V750 and V850

    Chester, thanks for chiming in! I’m hoping I can get the resolution to print at least to 24” on the short, 5” side of the neg. Sure hope so.

    Pere, you wrote, “...as the LR lens is focused on the glass surface”. Are you really, really sure about that? Wonder why Epson would provide vertically adjustable film holders to find optimum focus if the ...lens is focused on the glass surface”.
    I’m wondering what kind of focus tolerance really exists here. Epson would have to hold tolerances really tight to focus on a finite point “glass surface” from unit to unit. But one might luck out.
    Thanks Richard

  6. #6

    Re: Epson V750 and V850

    Ahhh! The Bell, I think I saw that someplace before. I own a small machine shop so I may be able to make a glass 5x7 carrier with a bit o’ luck.
    Thank you Pere.
    Cheers Richard

  7. #7

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    Re: Epson V750 and V850

    Quote Originally Posted by Richard Martel View Post
    Pere, you wrote, “...as the LR lens is focused on the glass surface”. Are you really, really sure about that? Wonder why Epson would provide vertically adjustable film holders to find optimum focus if the ...lens is focused on the glass surface”.

    Thanks Richard


    Yes, I'm sure, I checked it with a USAF 1951 glass slide. The high res lens is focused several mm on the glass, holders are adjustable because film can be curled and can effectively be one or two mm shifted from the right position.

    Instead the Low res lens covering the entire bed width is focused exactly on bed glass, it scans film and opaque documents that are placed on glass.

    ______

    in the past the 4990 previous model had a single lens that had to scan on bed and in the holders, so I guess focus was placed in an intermediate position, this is not the case of the V850, it has two specialized lenses, one for the holders and one for on bed.

    ______

    In this graph you have the optic performance depending on film height for the HR lens:

    Click image for larger version. 

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    Here you have the SNR depending on density
    Click image for larger version. 

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    _________________________

    Additional tips/resources:

    http://www.kennethleegallery.com/htm...ning/index.php
    https://files.support.epson.com/pdf/prv7ph/prv7phug.pdf

  8. #8

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    Re: Epson V750 and V850

    I also found on the V750 that scanning at 6400 and downsampling to 3200 get slightly more resolution than a direct 3200 scan. It's a visible difference but not more than that.

    7lasse

  9. #9

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    Re: Epson V750 and V850

    Quote Originally Posted by Richard Martel View Post
    Ahhh! The Bell, I think I saw that someplace before.
    It's the only way I have to make people see "my art"


    Quote Originally Posted by Richard Martel View Post
    I own a small machine shop so I may be able to make a glass 5x7 carrier with a bit o’ luck.
    You may depart from a V750 4x5 holder, that takes 5" in the hor direction:

    Attachment 195939

    Perhaps by removing the separator between both frames and with some polishing/machining you are done, you may substitute the doors by an ANR glass on film, like with V850 holders.

    The V850 holder makes a single frame and it has an ANR glass instead doors.

    Remember that the High Res lens is used by the scanner when a holder is detected, if you make your own holder then it has to keep the holder pads that are detected by the scanner to trigger the HR lens usage.



    Quote Originally Posted by lassethomas View Post
    I also found on the V750 that scanning at 6400 and downsampling to 3200 get slightly more resolution than a direct 3200 scan. It's a visible difference but not more than that.
    7lasse
    Of course !

    Some oversampling also helps to not loss IQ across edition.

    Here you have the effective resolution vs sampling density:

    https://archivehistory.jeksite.org/c.../appendixc.htm


    It shows average/min/max from several passes, depending on the pass result may vary because a bit depends on bars vs pixels aligment in each pass.

  10. #10

    Re: Epson V750 and V850

    funny I actually typed out "Pere Casels will chime in shortly and dispute this with charts, graphs, and links shortly" in my initial post. But then I deleted it, thinking it might be rude or that Pere might be out taking pictures. Nope!

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